Saturday, October 25, 2014

New paper finds why Earth is 2-3C cooler now than in the past, despite the same levels of CO2

A new study finds a

"different pattern of deep ocean circulation was responsible for the elevated temperatures 3 million years ago when the carbon dioxide level in the atmosphere was arguably what it is now and the temperature was 4 degree Fahrenheit higher. They say the formation of the ocean conveyor cooled the earth and created the climate we live in now."

Warmists prefer to claim that since CO2 levels today are about the same as during the Pliocene [5.333 million to 2.58 million years ago] and temperatures were 2-3C higher that we should expect the same 2-3C global warming to be "in the pipeline" in the near future. This new paper, however, finds

"the establishment of the modern deep ocean circulation – the ocean conveyor – about 2.7 million years ago [during the late Pliocene], and not a major change in carbon dioxide concentration in the atmosphere, triggered an expansion of the ice sheets in the Northern Hemisphere”

Therefore, due to increased heat transfer between the Northern and Southern Hemispheres from the establishment of the modern ocean conveyor belts, the oceans and globe have significantly cooled and we should not expect a temperature rise "in the pipeline" of an additional 2-3C for the same levels of CO2 today as were present during the Pliocene [even if one believes the climate is highly sensitive to CO2]. Further, climate models are unable to model or predict ocean oscillations and their complex interactions with other ocean and atmospheric oscillations and subsequent large-scale effects upon climate.

Note also the lack of correlation between temperature and CO2 levels on geologic timescales:

Most of the concerns about climate change have focused on the amount of greenhouse gases that have been released into the atmosphere.

But in a new study published in Science, a group of researchers have found that circulation of the ocean plays an equally important role in regulating the earth’s climate.

In their study, the researchers say the major cooling of Earth and continental ice build-up in the Northern Hemisphere 2.7 million years ago coincided with a shift in the circulation of the ocean – which pulls in heat and carbon dioxide in the Atlantic and moves them through the deep ocean from north to south until it’s released in the Pacific.

The ocean conveyor system, scientists believe, changed at the same time as a major expansion in the volume of the glaciers in the northern hemisphere as well as a substantial fall in sea levels. It was the Antarctic ice, they argue, that cut off heat exchange at the ocean's surface and forced it into deep water. They believe this caused global climate change at that time, not carbon dioxide in the atmosphere.

“We argue that it was the establishment of the modern deep ocean circulation – the ocean conveyor – about 2.7 million years ago, and not a major change in carbon dioxide concentration in the atmosphere that triggered an expansion of the ice sheets in the northern hemisphere,” says Stella Woodard, lead author and a post-doctoral researcher in the Department of Marine and Coastal Sciences at Rutgers University. Their findings, based on ocean sediment core samples between 2.5 million to 3.3 million years old, provide scientists with a deeper understanding of the mechanisms of climate change today.

The study shows that changes in heat distribution between the ocean basins is important for understanding future climate change. However, scientists can’t predict precisely what effect the carbon dioxide currently being pulled into the ocean from the atmosphere will have on climate. Still, they argue that since more carbon dioxide has been released in the past 200 years than any recent period in geological history, interactions between carbon dioxide, temperature changes and precipitation, and ocean circulation will result in profound changes.[non-sequitur]

Scientists believe that the different pattern of deep ocean circulation was responsible for the elevated temperatures 3 million years ago when the carbon dioxide level in the atmosphere was arguably what it is now and the temperature was 4 degree Fahrenheit higher. They say the formation of the ocean conveyor cooled the earth and created the climate we live in now.

“Our study suggests that changes in the storage of heat in the deep ocean could be as important to climate change as other hypotheses – tectonic activity or a drop in the carbon dioxide level – and likely led to one of the major climate transitions of the past 30 million years," says Yair Rosenthal, co-author and professor of marine and coastal sciences at Rutgers

The paper’s co-authors are Woodard, Rosenthal, Kenneth Miller and James Wright, both professors of earth and planetary sciences at Rutgers; Beverly Chiu, a Rutgers undergraduate majoring in earth and planetary sciences; and Kira Lawrence, associate professor of geology at Lafayette College in Easton.

Abstract: Earth’s climate underwent a major transition from the warmth of the late Pliocene, when global surface temperatures were ~2-3°C higher than today, to extensive Northern Hemisphere glaciation (NHG) at ~2.73 Ma. We show that North Pacific deep waters were significantly colder (4°C) and likely fresher than North Atlantic deep water prior to the intensification of NHG. At ~2.73 Ma, the Atlantic-Pacific temperature gradient was reduced to < 1°C suggesting the initiation of stronger heat transfer from the North Atlantic to the deep Pacific. We posit that increased glaciation of Antarctica, deduced from the 21 ± 10 m sea-level fall from 3.15-2.75 Ma, and the development of a strong polar halocline, fundamentally altered deep ocean circulation, which enhanced inter-hemispheric heat and salt transport thereby contributing to the NHG.